1. Field of the Invention
This invention relates to a booster circuit, and more particularly, to such a circuit for use in starting a DC motor or an electromagnetic trigger device for cameras.
2. Description of the Prior Art
In cinecameras in which a DC motor or an electromagnetic trigger device is used to drive the load, it is known to operate the release member by the attractive force of an electromagnet and to maintain such member in the attracted position during shooting. In such cases, it is often necessary to apply a high starting voltage only for starting the motor or the electromagnet and, after starting, to operate it at a steady but lower voltage. To meet such requirement, there is already proposed (in Japanese Patent Publication No. 4500/1972) a circuit in which a voltage of the DC source is boosted by an oscillator and a transformer to charge a capacitor by the boosted voltage so as to start a load such as a motor or electromagnet by the discharge energy of the capacitor, and thereafter the load is operated at a steady voltage from the power source. However, construction of such circuits are complicated since they require an oscillator and a transformer for obtaining the high voltage.